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The numerical data obtained by iSALE are stored in a strongly compressed, flexible, and (nearly) lossless manner. The File I/O of iSALE, iSALEPlot, vimod and other tools is performed in a user-friendly way by a separate library, libjc. This library is developed with iSALE and vimod and is provided with iSALE.

This technique uses a Lempel-Ziv-Storer-Szymanski algorithm for a lossless compression of the data. Again, the compressed data is sorted with a huffman-code for further reduction of the required disc-space.

This technique works like the GZIP-technique described above, except that each value is mapped from 32-bit-floating-point domain to a 16-bit unsigned int domain before compression. The width of the transformation domain is controlled by a quality-parameter q. q=50 means, only 50% of the 16-bits are used for mapping. The transformation procedure can be described by following formula:

Not every compression technique is lossless. The compression error is not only dependent on the chosen technique and the compression density (quality-factor q), but also on the nature of the given field. Here we present the results of some tests for the commonly used fields...